What are the solutions to the equation 0 = x2 – x – 6?

Factor to this equation out, the easiest way is to solve for the two x values that add up to -1 but when multiplied is equal to -6. It should look like this: (x +- ?)(x +- ?). 
The factored out form is then (x - 3)(x +2), because -3 + 2 = -1 and when multiplied together gives -6. 
x - 3 = 0
x = 3
x + 2 = 0
x = -2
The two solutions are therefore, x = 3 and x = -2. 

Hope it helps

This  can be factored- 
x^2 - x - 6 = 0
= x^2 - 3x + 2x - 6= 0
= x(x - 3) +  2(x - 3) = 0
= (x + 2)(x - 3) = 0 
x+2 = 0 gives x = -2 and x - 3 = 0 gives x = 3

so the solution set is {-2, 3}